How to serial-over-lan past “Loading initial ramdisk”?

Question

I'd like to use "ipmitool ... sol activate" to record any kernel panics that may happen. I managed to keep GRUB2 in text-mode with "GRUB_TERMINAL=console" in /etc/default/grub. But right after the message "Loading initial ramdisk" (which is still GRUB), when Linux starts printing text on VGA console, messages on the serial console stop.

I guess either GRUB or Linux is doing something at that point, like loading a font, which kills off the vga-text-to-serial line. I'd like to keep it from doing that, whatever it is.

I have tried so far:

• Kernel options "nofb nomodeset text" (the latter being for other Distros, I think).
• GRUB_GFXPAYLOAD_LINUX=text

One obvious alternative is to setup serial console redirection to the virtual COM port, which should make panics appear on the serial-over-lan as well, but I'd prefer to stay in the initial text-mode, so VGA and console are in sync and both accept input.

Answer 1

By default kernel does not output anything to serial ports. You should explictly mention it.
To solve this add following to GRUB_CMDLINE_LINUX_DEFAULT

console=tty0 console=ttyS0,9600n8

replace 9600n8 with your sol console settings.